Some might be familiar with so-called balcony power plants with storage. These have intelligent features that monitor my household’s electricity consumption and, with the help of the storage, inject exactly the right amount of power to achieve zero feed-in
Now I want something similiar like that. I have 2 Sonoff S60 Smartmeter and now one is plugged at my microinverter and one at a heater as example.
My solar produce now 800W energy, so I want, that my heater is using maximum 800W. If my solar produce later 400W energy, so the maximum output at the heater is 400W. If my solar produce 600W, then it will go up to 600W automatically.
The Sonoff S60 only measures the current drawn by the receiver, it doesn't "match"
the receiver's power to the current power source's efficiency. If I understand your
goal correctly, in the simplest case, you need a PWM circuit with MPPT between the
panels and the radiator. This can be done cheaply with an Arduino or ESP32 for a few
bucks. I played around with this last year and posted the schematics and program code
in this forum thread, but I didn't finish it because I got bored. If anyone is
interested, check out the MPPT function at the end of the thread; it already works
really well. ;) https://www.elektroda.pl/rtvforum/topic2948683-720.html
What you’re talking about, about modulating the power of your electric water heater, can be done using PWM technology and programmed around an ESP32. That system isn’t integrated with eWeLink unless they release something very specific. You could do it from HOME ASSISTANT, but that’s not only non-trivial, but also beyond the scope of this forum.
I don’t have Home Assistant. But I saw it from some other Brands (like Marstek or Ecoflow). But they also use their own System(battery and Smartmeter). But I dont want buy a battery because it is too expensive now. I only want it for my solar system.
Thought it would be possible in the future, because I can choose something like >100W, then turn on Device X or <100W turn off Device X.
You may be able to do something similar to modulate your water heater. That said with only a few Watts going into it, it might not get very hot unless you have a second low power immersion heater in the tank. These are available for direct solar water heating I know someone who did a low power solar water heater successfully.
Backyard solar
Cheap solar project to offset quiescent energy use when the house is unoccupied and there are no other useful options for using the energy.
e.g. hot water good, no car charging, no lights, towel rails, washing, drying etc
Hardware
Shelly EM version 1 - Underpower URL is set so when load is below 25 Watts the Node-Red flow (See Kick Dump.js)is kicked to regulate the Dump Load Dimmer switch.
***var absdp = Math.abs(ShellyEM - DumpDeadBand);
DumpPower += (absdp * DumpPgain);
AliExpress part Tuya Dimmer Hacked a Hubitat community driver by “Matt Hammond” to get it working with the _TZ3000_kvwrdf47
def cfg = [" _TZ3000_kvwrdf47": [ numEps: 2, joinName: “Tuya Zigbee 2-Gang Dimmer module” ]]
See Greenway Tuya Zigbee dimmer module.groovy Greenway Tuya Zigbee dimmer module.groovy (16.2 KB)
Function
Stop solar export in low load situations, which does happen when the house is unoccupied
